Construction will start this summer on a long-planned apartment development in Central Square, after it won final approval from the Cambridge Planning Board Tuesday.

Developer Twining Properties expects to launch work soon on Mass+Main, a two-building, 285-unit development at the corner of Massachusetts Ave. and Columbia Street that will replace a garage and former medical testing facility with one of the tallest buildings in that section of Cambridge. The builders have to set aside 20 percent of units at affordable rents, partly in exchange for being allow to build 195 feet high.